The new tax bill unveiled by House Republicans Thursday is so simple that taxpayers will be able to file using a postcard, according to GOP lawmakers.

"This is a complete redesign of the code, so we can simplify it so much that 9 out of 10 Americans can file using a postcard-style system, lowering the rates, protecting more of the first dollars you earn," said Rep. Kevin Brady, R-Texas, while holding up a mock-up of the tax postcard. "We're not just putting higher octane fuel in an old clunker of a tax car, we've proposed to drive a newer tax car that can beat and win against any country in the world."

The new plan aims, in part, to lower the corporate tax rate to 20 percent.

The Tax Cuts and Jobs Act — the bill's official name — would also slash the number of income tax brackets from seven to four: 12 percent, 25 percent, 35 percent and 39.6 percent. Republican leaders have rallied behind the idea of tax reform, as President Donald Trump's campaign leaned heavily on promising substantive tax change.

"It's redesigned for simplicity, fairness and benefits," Brady added. "I predict, under this tax reform plan, America will evolve from 31st in the world among our competitors to the top 3 as the best places on the planet for the best new job, that next new manufacturing plant."

Because much of the company's appeal derives from do-it-yourself tax return assistance, news of a simplified tax code could be seen as a threat. The stock is off more than 24 percent from its 52-week high, with much of that decline coming since the summer as details about the simplified tax plan began to emerge.

"It's going to make life very simple," said President Trump later in the day. "The only people that aren't going to like this is H&R Block. They're not going to be very happy. That's probably one of the only companies in the country that's not going to be thrilled."

Shares of H&R Block ticked added slightly more to their losses after the president's comments.